1. Field of the Invention
The present invention relates to a hub assembly, and more specifically, to a playpen hub assembly.
2. Description of the Prior Art
In general, a hub assembly for a playpen comprises a base and a plurality of support pipes pivoted to the base in a radial manner. A lock device is commonly disposed on the base for avoiding erroneous playpen folding operations. In other words, when the playpen hub assembly is in an unfolded state, the lock device may constrain rotation of the plurality of support pipes relative to the base so that the plurality of support pipes and the base may provide steady support for objects placed on the playpen. On the other hand, when a user wants to fold up the playpen, the user just needs to lift the lock device upward to release restriction of the lock device for the plurality of support pipes so that the plurality of support pipes may rotate relative to the base accordingly. In such a manner, the user may fold the playpen up easily. A lateral engagement method and a vertical engagement method are commonly applied to structural designs of the said lock device. The lateral engagement method involves utilizing knife-shaped hooks to hook the plurality of support pipes laterally for constraining rotation of the plurality of support pipes relative to the base. However, this method usually requires a complicated structural design for assuring that each knife-shaped hook may hook a corresponding support pipe laterally. Furthermore, the vertical engagement method involves utilizing a hook formed on the base to vertically engage with a corresponding slot on one support pipe for constraining rotation of the support pipe relative to the base. That is to say, when the user wants to fold the playpen up, the user just needs to lift the hook of the base upward to release engagement of the hook and the slot so that the support pipe may rotate relative to the base accordingly. Thus, this method may allow the user to fold the playpen up easily and quickly. However, in playpen structural design, disposal of a two-step lock device in a playpen is necessary for safety concerns. In other words, for operational safety, the user needs to perform two release operations to fold up the playpen. Therefore, although the said vertical engagement method may allow the user to fold up the playpen easily and quickly, this method still has safety concerns in use, since this method only requires the user to perform one lifting operation to complete the playpen folding process.